<html xmlns="http://www.w3.org/1999/xhtml" 
      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
      
<head>
</head>
<body>

<div style="float: left">X<xul:hbox><input type="radio"/></xul:hbox></div>
<div id="y" style="float: left">Y</div>

</body>
</html>
